Java 1D Array ⬀
An array is a simple data structure used to store a collection of data in a contiguous block of memory. Each element in the collection is accessed using an index, and the elements are easy to find because they're stored sequentially in memory.
Because the collection of elements in an array
is stored as a big block of data, we typically
use arrays when we know exactly how many pieces
of data we're going to have. For example, you
might use an array to store a list of student
ID numbers, or the names of state capitals. To
create an array of integers named myArray
that can hold four integer values, you would
write the following code:
int[] myArray = new int[4];
This sets aside a block of memory that's
capable of storing 4 integers. Each integer
storage cell is assigned a unique index ranging
from 0 to one less than the size of the
array, and each cell initially contains a 0.
In the case of myArray, we can store integers
at indices 0, 1, 2, and 3. Let's say we
wanted the last cell to store the number 12;
to do this, we write:
myArray[3] = 12;
Similarly, we can print the contents of the last cell with the following code:
System.out.println(myArray[3]);
The code above prints the value stored at index
3 of myArray, which is 12 (the value we
previously stored there). It's important to
note that while Java initializes each cell of
an array of integers with a 0, not all
languages do this.
The code in your editor does the following:
- Reads an integer from stdin and saves it to
a variable,
n, denoting some number of integers. - Reads
nintegers corresponding toa₀,a₁,...,aₙ₋₁from stdin and saves each integeraᵢto a variable,val. - Attempts to print each element of an array of integers named
a.
Write the following code in the unlocked portion of your editor:
- Create an array,
a, capable of holdingnintegers. - Modify the code in the loop so that it saves
each sequential value to its corresponding
location in the array. For example, the first
value must be stored in
a₀, the second value must be stored ina₁, and so on.
Good luck!
The first line contains a single integer, n,
denoting the size of the array.
Each line i of the n subsequent lines
contains a single integer denoting the value of
element a₁.
You are not responsible for printing any output
to stdout. Locked code in the editor loops
through array a and prints each sequential
element on a new line.
5
10
20
30
40
50
10
20
30
40
50
When we save each integer to its corresponding
index in a, we get a=[10,20,30,40,50]. The
locked code prints each array element on a new
line from left to right.